Fluidic hot and cold pressure forming apparatus

ABSTRACT

An apparatus comprises a hot and a cold fluid reservoirs joined through a conduit and valving system to one or more pair of expandable bladders. A pump is engaged with the conduit system so as to enable the directing of the hot fluid from one of the reservoirs to one or more of the bladders and to enable directing the cold fluid from the other of the reservoirs to one or more of the other of the bladders. The bladders are mutually joined such that with either the hot or the cold bladders filled, both of the bladders are pressed against one or more workpieces, whereby heat is delivered to the workpieces when the one of the bladders, of each pair, is filled, and heat is extracted from the workpieces when the other, of each pair, of the bladders is filled while the other is deflated.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to forming operations and moreparticularly to a fluid based molding apparatus and method capable ofdelivering pressure and heat energy to a workpiece or withdrawal of heatenergy from a workpiece.

2. Description of Related Art

The following art defines the present state of this field:

Rudy, U.S. Pat. No. 3,760,056 describes an improved method for customfitting an inflatable bladder (e.g., for ski boots or the like) to aportion of a person's anatomy (e.g., a wearer's foot). The inflatablebladder is made of a suitable elastomer (e.g., ether base polyurethane)which may be heated, distended and then cooled to room temperature toset the bladder in the distended shape. A preferred embodiment of theimproved method comprises placing the inflatable bladder on a wearer'sfoot, placing the boot to be worn on the wearer's foot over the bladder,heating the bladder, inflating the bladder to a desired pressure toforce the bladder into intimate contact with the wear's foot and coolingthe bladder to room temperature to set it in its distended shape. Thebladder, which now conforms to the contour of the wearer's foot, isdeflated and the boot and bladder are removed. When the bladder is laterre-inflated, it will custom fit the wearer's foot. Preferably, theelastomer from which the bladder is made will return to its originalshape when reheated. Thus, the bladder may be reheated to restore it toits original shape, and the process of the present invention may bere-employed to custom fit the bladder to a different foot.

Waters, U.S. Pat. No. 4,623,497 describes a mold for molding articles ofplastic or other like materials, having a plurality of verticallyextending internal passages, is connected by inlet and return conduitsinto a closed loop that includes a heat exchanger partially filled witha liquid supply of a cooling fluid or a heating fluid. For cooling theheat exchanger is positioned with its liquid level above the top of themold, the inlet conduit connects the lower part of the heat exchanger,below the liquid level, to the lower ends of the mold passages, and thereturn conduit connects the upper ends of the mold passages to the upperpart of the heat exchanger; for heating these relationships arereversed. In operation the fluid changes its physical state at criticalpoints in the mold passages, going from liquid to vapor for cooling andfrom vapor to liquid for heating; circulation in the closed loop is inresponse to the effect of gravity. Operation of the heat exchanger iscontrolled to maintain a controlled pressure in the closed loop.

Maus et al., U.S. Pat. No. 5,376,317 describes an improved optical diskfor information storage and holographic imaging, and optical lenses andreflective optical elements which are among the difficult-to-moldthermoplastic products which require precision replication of themolding surfaces, in micro detail. By heating (with circulating heattransfer fluids supplied by a hot side reservoir) these mold surfaces toa temperature setpoint sufficiently high to retard solidification andpremature viscoelastic skinning of the molten thermoplastic injectedinto the mold cavity, superior quality molded surfaces can be formed bythe plastic, which is then rapidly cooled to solidification (bycirculating heat transfer fluids supplied from a cold side reservoir).Each injection molding cycle thus starts with a heating phase, whereinmolding surface temperature increase is thermally driven by hot sidereservoir fluid temperatures above the melt-solidifying temperatures (Tgor Tm) characteristic to the thermoplastic, followed by a cooling phase,wherein molding surface temperature decrease is thermally driven by coldside reservoir fluid temperatures below the melt-solidifyingtemperatures (Tg or Tm) characteristic to the thermoplastic. The greaterthese temperature differences are, the faster the molding cycle will be.Fluid control units and electronic process sequence control units areinterconnected to govern the flow of these fluids into and out of theinjection mold and the reservoirs in accordance with the predeterminedlogic of the process flowsheet.

Gaworowski et al., U.S. Pat. No. 5,795,536 describes a method andapparatus for the rapid, uniform curing of cylindrical, polymericobjects. The invention provides precise, accurate control of both thecuring temperature and pressure because the heating system isindependent of the pressurization device. Cylindrical polymeric objectsare cured by mounting the object on a cylindrical mandrel, applyingsubstantially uniform pressure to the outer surface of the object,typically through an expandable bladder, and supplying curing is heatdirectly to the object by circulating a liquid heat transfer mediumthrough the bladder or mandrel. Preferably, the expandable elastomericbladder is mounted coaxially with the mandrel, and is expanded with asuitable liquid or gas to provide the pressure. The liquid heat transfermedium can be pumped through a passage in the mandrel to apply heatdirectly to the interior of the object, or the liquid heat transfermedium may be used to expand the bladder and apply the curing heat tothe exterior of the object. Alternatively, a combination of bothtechniques may be employed.

Kristinsson, U.S. Pat. No. 5,885,509 describes a prosthesis socketcasting device including a base member on which an elongated annularmolding bladder is mounted, the bladder peripherally enclosing agenerally centrally located casting area and extendable when inflatedfrom the forward side of the base. The bladder is formed of a pliable,air impermeable, relatively non-stretchable sheet material enclosing, incooperation with the base, an air chamber peripherally surrounding thecasting area. The casting area includes an open residual limb receivingend and extends from such end to the base, and an inflation system forthe bladder is provided. The casting device may be used in conjunctionwith a prosthesis suction socket that includes a tension member at itsdistal end connectable to the base member during a casting procedure.Moldable and settable prosthesis socket or other moldable castingmaterial is placed over the suction socket and is compression molded bythe inflated bladder while the casting material cures. During thecompression casting procedure, a tension force resulting from thebladder inflation pressure may be applied to the distal end of thesuction socket to elongate and distend the distal area of the residuallimb against which the casting material is formed under pressure. Thebladder is rollable relative to the base member to provide ready accessto the tension member connector carried by the base member.

Van Ert, U.S. Pat. No. 5,928,597 describes a method of thermoformingsheet articles including: a) heating a sheet article to be thermoformed;b) inserting the heated sheet article into a pressure vessel havingfirst and second vessel halves, wherein each vessel half includes aliquid chamber and a thin shell configured for forming the sheet articleto a desired shape; c) closing the pressure vessels such that the sheetarticle is captured between the thin shells; and d) providing liquid ofequal pressure in each liquid chamber to force the thin shells togetherto form the sheet article to the desired shape and to draw heat awayfrom the thin shells for cooling the sheet article.

Foltuz et al., U.S. Pat. No. 6,196,830 describes a water jacket assemblyfor use in injection mold systems, and particularly with heterocavityinjection mold systems. The water jacket assembly comprises a sleeveconstruction of material with high heat-transfer properties. A conduitis beveled into the outside perimeter of the sleeve forming acirculation channel. The inside perimeter of the sleeve is fashioned toreceive an individual injection mold. A mold base slideably received thewater jacket and cooling fluid is circulated from the mold base throughcirculation channel in the water jacket, and then back to the mold base.A fluid input plug and fluid output plug extend from the mold base andare received by the apertures in the individual mold for additionalcooling.

The prior art teaches the use of hot and cold fluids for thermoformingarticles. Rudy, U.S. Pat. No. 3,760,056 teaches the inflation of a bootbladder while heat is applied to mold the bladder to the shape of afoot. The prior art does not teach the use of dual or paired bladdersand dual fluid reservoirs (hot and cold) so that thermal energy may bequickly injected into the workpiece or withdrawn from the workpiece. Thepresent invention fulfills these needs and provides further relatedadvantages as described in the following summary.

SUMMARY OF THE INVENTION

The present invention teaches certain benefits in construction and usewhich give rise to the objectives described below.

The present invention is an apparatus comprising a hot and a cold fluidreservoirs joined through a conduit and valving system to one or morepair of expandable bladders. A pump is engaged with the conduit systemso as to enable the directing of the hot fluid from one of thereservoirs to one ore more of the bladders and to enable directing thecold fluid from the other of the reservoirs to one or more of the otherof the bladders. The bladders are mutually joined such that with eitherthe hot or the cold bladders filled, both of the bladders are pressedagainst one or more workpieces, whereby heat is delivered to theworkpieces when the one of the bladders, of each pair, is filled, andheat is extracted from the workpieces when the other, of each pair, ofthe bladders is filled while the other is deflated. Such an apparatus isuseful for molding cast materials used in medicine to allow rapidforming. The present invention provides the advantages of applying aselectable pressure evenly to an injured portion of the body forapplying cold or hot fluid, i.e., a cold or hot compress, as is known inthe healing arts. The pressure and temperature may be applied to a castfor setting the cast to the exact shape of an arm, leg or other portionof the body. The same technique may be applied to forming the interiorof boots, such as for skiing, mountain climbing and other sports, to theexact shape of the foot. The apparatus may also be used to pressure formplastics around a male mold or into a female mold to replace vacuumforming.

A primary objective of the present invention is to provide an apparatusand method of use of such apparatus that provides advantages not taughtby the prior art.

Another objective is to provide such an invention capable of providingthermal energy to, or withdrawing it from, a workpiece.

A further objective is to provide such an invention capable of providingsuch thermal energy transfer while also applying hydraulic pressure to aworkpiece surface.

A still further objective is to provide such an invention capable ofbeing wrapped about a workpiece having a diameter selected from a rangeof diameters, i.e., the invention may accommodate a wider range ofworkpiece diameters.

A yet further objective is to provide such an invention capable of beingoperated only when a data transmission element of the invention isoperating.

Other features and advantages of the present invention will becomeapparent from the following more detailed description, taken inconjunction with the accompanying drawings, which illustrate, by way ofexample, the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate the present invention. In suchdrawings:

FIG. 1 is a mechanical schematic of a preferred embodiment of theinvention shown with bladders of the invention deflated;

FIG. 2 is similar to FIG. 1 but showing the bladders as inflated with ahot fluid; and

FIG. 3 is a mechanical schematic of a further preferred embodiment ofthe invention.

DETAILED DESCRIPTION OF THE INVENTION

The above described drawing figures illustrate the invention in at leastone of its preferred embodiments, which is further defined in detail inthe following description.

The present invention is an apparatus comprising, in one embodiment,shown in FIGS. 1 and 2, a pair of fluid reservoirs identified bynumerals 10 and 15, which are joined through a conduit system 20 toplural pairs of expandable bladders 30. A pump 40 is engaged with theconduit system 20, as shown in FIG. 1, so as to enable the directing ofa hot fluid 15′ from the reservoir 15 to one of the bladders 32 of eachpair of bladders 30, and to enable directing a cold fluid 10′ from thereservoir 10 to the other of the bladders 34 in each pair. The bladders32, 34 are mutually joined together such that when either of thebladders is filled with fluid (10′ or 15′), both of the bladders 32, 34are pressed against a workpiece 50, as shown in FIG. 2, due to theexpansion of either one of the bladders. In FIG. 2 we see that bladders32 are filled while bladders 34 are fully deflated. FIG. 2 serves toillustrate the expansion of either of the bladders 32 or 34 since thesame result is achieved, i.e., the expansion of the bladder pair againstthe workpiece 50, although with opposite thermal flow. The bladdermaterial is preferably selected for efficiently carrying thermal energyacross it from the fluid to the workpiece or from the workpiece to thefluid. Such a material may be a carbon filled rubber.

Thus, heat is delivered to the workpiece 50 when the bladders 32 arefilled, and heat is extracted from the workpiece 50 when the bladders 34is filled. FIGS. 1 and 2 illustrate a setup whereby, for instance a pairof form fitting boot interiors may be formed to fit a person's feet. Inthis case, the bladders are forced, with pressure, against a thermallypliable boot liner (the workpiece 50), which is then forced intointimate contact with feet 50′. After the workpiece 50 is formed to theshape of the feet under pressure and heat driven by bladders 32 withfluid 15′, the fluid 15′ is very quickly drawn out of bladders 32 andfluid 10′ is forced into bladders 34. This cold fluid 10′ is then usedto set the moldable workpiece 50. In an alternate embodiment, two pumpsmay be used to simultaneously draw one fluid out of one set of thebladders while the other set of the bladders is being filled. Generally,this is not necessary since the fluid may be moved rapidly between thebladders 32, 34 and the reservoirs 10, 15.

To understand how the conduit system operates, it is clear that whenvalves V4 and V6 are open, pump 40 is able to deliver hot fluid 15′ tobladders 32. When V1 and V5 are open, pump 40 is able to deliver coldfluid 10′ to bladders 34. This assumes that the remainder of the valvesare all closed in both cases. To withdraw fluid from the bladders, V2 orV3 is then opened and V1 and V4 are closed for directing the cold 10′and the hot 15′ fluids respectively. An electrical valve timer andcontroller 60, also referred to as a controlling means, is used tooperate and sequence the valves. The controller 60 is therefore placedinto electrical communication with the valves V1-V6 as is well known inthe art. Controller 60 also controls a pressure regulator R and a heatexchanger X for setting the appropriate fluid pressure and temperaturesfor each application. Heat exchanger X may be a simple resistance heateror a true heat exchanger whereby a common heat pump is used to movethermal energy between the fluids in the reservoirs 10 and 15. Such aheat pump, it operation and structure is very well known in the art. Thecoil symbol for the heat exchangers X represent that portion of the heatpump that is immersed within the fluid for delivery or extraction ofthermal energy.

A slight variant on the above described system is shown in FIG. 3. Inthis case the pair of bladders 32, 34 are formed to encircle theworkpiece 50, and a means for fastening 70 of the bladders in placeabout the workpiece is provided. In this approach, the bladders may beplaced in face-to-face relationship as previously discussed, or they maybe positioned one within the other, as is shown in FIG. 3. In thislatter case, the two bladders are formed as a tube within a tube so thatthis tube assembly is able to be wrapped around a workpiece such as amoldable cast placed about an arm or a leg where a broken bone has beenset. The Fastening means 70 may be Velcro® fastening materials so thatthe bladders may be wrapped to a selected tightness about the castworkpiece, and then easily fastened in place.

The controller 60 preferably is enabled for transmitting datacorresponding to usage of the apparatus. This may be enabled in manyways, but preferably the controller is interconnected via the publictelephone network, for instance, using a modem 62 connected to atelephony network TTY, to automatically make signal connection with aremote recording apparatus, such as a computer, for recording each timethe present invention is used. In this way a billing-per-use accountingsystem may be set up and operated. This is shown in FIG. 3.

Preferably, the controlling means 60 is enabled for activating theapparatus only when data transmitting is operable. For instance, if themodem is not operating, or if the remote recording apparatus is noton-line, so as to receive a wait response from the remote recordingapparatus at the controller, the controller will not operate. Thisinsures proper recording for billing purposes. In this respect thecontroller is set with logic to process the method of the presentinvention, or instance when the following set of conditions are met:pressure in range, temperature of each fluid in range, valves, regulatorand pump operating properly, remote recording apparatus on line.

The overflow and pressure cap devices shown in the figures are wellknown in the art in such fluid systems and are therefore not describedfurther herein.

While the invention has been described with reference to at least onepreferred embodiment, it is to be clearly understood by those skilled inthe art that the invention is not limited thereto. Rather, the scope ofthe invention is to be interpreted only in conjunction with the appendedclaims.

What is claimed is:
 1. An apparatus comprising: a pair of fluidreservoirs joined through a conduit system to a pair of expandablebladders positioned for encircling a workpiece, a pump engaged with theconduit system so as to enable the directing of a hot fluid from one ofthe reservoirs to one of the bladders and to enable directing a coldfluid from the other of the reservoirs to the other of the bladders; thebladders mutually joined such that with one of the bladders filled, theone of the bladders is pressed against the workpiece, and with the otherof the bladders filled, the pair of the bladders are pressed against theworkpiece; whereby heat is delivered to the workpiece when the one ofthe bladders is filled, and heat is extracted from the workpiece whenthe other of the bladders is filled.
 2. The apparatus of claim 1 furthercomprising a controlling means enabled for transmitting datacorresponding to usage of the apparatus.
 3. The apparatus of claim 2wherein the controlling means is enabled for activating the apparatusonly when data transmitting is operable.
 4. The apparatus of claim 1further comprising a means for exchanging heat energy between the hotfluid and the cold fluid.
 5. An apparatus comprising: a pair of fluidreservoirs joined through a conduit system to two pair of expandablebladders positioned in opposing juxtaposition and spaced apart forreceiving a workpiece therebetween, a pump engaged with the conduitsystem so as to enable the directing of a hot fluid from one of thereservoirs to one of the bladders in each of the pairs of the bladders,and to enable directing a cold fluid from the other of the reservoirs tothe other of the bladders in each of the pairs of the bladders; each ofthe pairs of the bladders mutually joined such that with one of thebladders of each of the pairs of the bladders filled, one of thebladders of each of the pairs of bladders is pressed against one of twoopposing sides of a workpiece, whereby heat is delivered to theworkpiece when the one of the bladders of each of the pairs of bladdersare filled, and heat is extracted from the workpiece when the other ofthe bladders of each of the pairs of the bladders are filled.
 6. Theapparatus of claim 5 further comprising a controlling means enabled fortransmitting data corresponding to usage of the apparatus.
 7. Theapparatus of claim 6 wherein the controlling means is enabled foractivating the apparatus only when data transmitting is enabled.
 8. Theapparatus of claim 5 further comprising a means for exchanging heatenergy between the hot fluid and the cold fluid.